There is no such thing as priority for PlaylistApplicationResources. This is because they are never unloaded from memory, like normal application resources can be. If the memory becomes too full, the HD DVD player automatically starts deleting unused resources (resources not valid for that time period or title). The priority is used to determine which items are deleted first.

The playlist application is always running, so there is no time at which its resources are not valid. Therefore, no need for a priority attribute.

In the future, playlist schema validation would be a very useful tool for your debugging. The schema can be found here: